What is Protein? - Definition, Function, Benefits & Sources

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  • 0:02 Protein: The Inside Story
  • 0:48 Amino Acids & Proteins
  • 1:25 Sources of Protein
  • 2:37 Lesson Summary
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Lesson Transcript
Instructor: Dominic Corsini
In this lesson, you'll learn about the primary structure, function, and sources of protein molecules while exploring some real-world examples and illustrations.

Protein: The Inside Story

The human body uses proteins for many things, including repairing and building tissues, acting as enzymes, aiding the immune system, and serving as hormones. Each of these important functions requires a slightly different form of protein. In spite of their differences in structure, all proteins contain the same basic sub-components.

Proteins are one of the four different types of macromolecules, in addition to carbohydrates, lipids, or fats, and nucleic acids, such as DNA and RNA. Macromolecules are large molecules that perform specialized functions inside living organisms. The structural arrangement of a protein molecule will differ in accordance with its function.

Amino Acids & Proteins

Proteins are long chains of amino acids. Amino acids are the building blocks of protein. In other words, amino acids are like the links in a chain. The chain itself represents the protein molecule. Protein chains are then twisted and folded together in specific ways to create certain molecules.

This example shows our primary protein chain as it's twisted into a helical shape, folded into a sheet, and then twisted all over again into an intricate globular shape. In this case, the final product is a protein molecule known as hemoglobin, which can be found in your blood.

Sources of Protein

Earlier, we mentioned that protein plays a role in tissue repair, and that's why it's so important to have protein in your diet. But what are the best sources of protein? And, are there different types of protein? Let's explore these questions. Afterwards, you might take a look in your refrigerator and decide whether your diet is protein rich or protein poor.

Protein can be found in all living things. The type and amount of protein within foods can vary, but inevitably, it's there in some form. Meats, cheeses, and nuts tend to have a higher protein content than many plant-based sources. To determine the protein content of a food, we'll need to read its nutrition label.

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